Donald Trump

Updated at 2:20 p.m. ET

As Turkish soldiers launched an assault on U.S.-backed Kurdish fighters in northern Syria and panicked civilians fled the battle zone, the White House sought to tamp down intense criticism over what many view as Washington's acquiescence in the incursion.

Turkey's forces crossed the border on Wednesday, carrying out airstrikes and artillery barrages against the Syrian Democratic Forces, a Kurdish-led militia that has fought alongside the U.S. in efforts to dismantle the Islamic State in Syria.

Former Vice President Joe Biden called for President Trump's impeachment and removal from office, on Wednesday.

Up until now, Biden had reserved judgment, saying he supported the House's impeachment inquiry and wanted to see what the facts showed.

But in a campaign speech in Rochester, N.H., Biden was unequivocal, saying that "to preserve our Constitution, our democracy, our basic integrity, [Trump] should be impeached."

Biden said the case was already clear before the public.

President Trump is refusing to cooperate with House Democrats' impeachment inquiry and will provide neither documents nor members of his administration to testify.

The White House laid out a multifaceted legal argument in a letter to House Speaker Nancy Pelosi, D-Calif., in which it charged that the inquiry is invalid and "violates the Constitution, the rule of law, and every past precedent."

Updated at 2:20 p.m. ET

Turkish forces began crossing the Syrian border on Wednesday, launching an operation in Kurdish-dominated areas of the country's north, President Recep Tayyip Erdogan announced.

The Turkish offensive jeopardizes Kurdish-led forces who have been a key U.S. ally in the bloody fight against ISIS. Turkey says those same forces are linked to militant groups who stage attacks in a separatist movement against the Turkish government.

President Trump says his request for Ukraine to investigate former Vice President Joe Biden was driven by his concerns about corruption.

"This is not about politics, this is about corruption," Trump said last week. "If you look and you read our Constitution and many other things, I have an obligation to look at corruption."

But anti-corruption advocates say his administration's record of fighting corruption is weak and not in line with Trump's rhetoric.

The Russian government's interference in the 2016 U.S. elections singled out African Americans, a new Senate committee report concludes.

Using Facebook pages, Instagram content and Twitter posts, Russian information operatives working for the Internet Research Agency had an "overwhelming operational emphasis on race ... no single group of Americans was targeted ... more than African Americans."

While the impeachment inquiry plays out in Washington, the political drama is also fodder for the classroom.

High school civics and government teachers across the country are now wrestling with the material that the impeachment provides. Many must tread carefully around hot-button political issues, while walking their students through America’s founding documents.

As President Trump defends his decision to pull away some U.S. troops from Syria's border with Turkey, the president's former envoy for the fight against the so-called Islamic State is raising alarms about how potentially destabilizing the move can be for the region.

President Trump will present the Medal of Freedom, the nation's highest civilian honor Tuesday, to a former top aide to President Ronald Reagan who has been a stalwart of the conservative movement for the past half-century.

Edwin Meese III, always known as Ed, is a native Californian and a living reminder of the time when the Republican Party counted on the Golden State as the cornerstone of its Electoral College majorities.